Application manages the IP layer topology information - Interfaces

Change-Id: Ie1dea035674ee98583e98a82cca7e33ab0858b92
diff --git a/apps/iptopology-api/src/main/java/org/onosproject/iptopology/api/TopologyId.java b/apps/iptopology-api/src/main/java/org/onosproject/iptopology/api/TopologyId.java
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+++ b/apps/iptopology-api/src/main/java/org/onosproject/iptopology/api/TopologyId.java
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+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.iptopology.api;
+
+import java.util.Objects;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * Represents Multi-Topology IDs for a network link, node or prefix.
+ */
+public class TopologyId {
+    private final short topologyId;
+
+    /**
+     * Constructor to initialize its parameter.
+     *
+     * @param topologyId topology id for node/link/prefix
+     */
+    public TopologyId(short topologyId) {
+        this.topologyId = topologyId;
+    }
+
+    /**
+     * Obtains the topology ID.
+     *
+     * @return  topology ID
+     */
+    public short topologyId() {
+        return topologyId;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(topologyId);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj instanceof TopologyId) {
+            TopologyId other = (TopologyId) obj;
+            return Objects.equals(topologyId, other.topologyId);
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("topologyId", topologyId)
+                .toString();
+    }
+}
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